If you own a modern 4WD then you may well have seen, at one time or another, the dreaded Check Engine Light. It’s infuriating, as well as deflating, because it can often spell out the need for serious mechanical work. Before you start wondering if you can dip into the super fund for a new engine, take a deep breath because it may not be as bad as it first seems.

Generally speaking, Check Engine Lights come on when some sort of sensor in the vehicle detects an abnormal occurrence. That’s very vague, because it could be any one of three dozen different sensors in a modern vehicle. We’ve personally seen Check Engine Lights come on because an ABS sensor was detecting too much wheelspin in sand!

There are ways to find out what a Check Engine Light actually means. The first method involves getting a length of wire, stripping the ends of the insulation back and bridging out two pins in a diagnosis port. Then, when that occurs, you have to count the number of times the Check Engine Light flashes briefly, and how many times it flashes longer and slower. The brief flashes correspond to one number, the longer flashes to another and together they give you a code you can look up.

The much, much simpler way to read a Check Engine Light is with an Engine Data Scan. Just plug it into your OBDII port, and it’ll store and read any error codes that come up, before displaying them. Then, all you have to do is plug that code into Google and it’ll tell you exact what’s up.

But what happens when a vehicle goes into Limp Mode? This is when a Check Engine Light displays on the dash, but there’s a severe-enough problem that the vehicle’s computer limits performance to the point where the vehicle is only just able to move under its own steam. The idea is it can be ‘limped’ into a mechanic without the risk of further damage.

So where does an EDS come into this scenario? Sure, it can read engine fault codes and tell you what caused the Check Engine Light, but it can’t magically fix anything, can it? Truth be told, your first and biggest diagnosis weapon in your arsenal is the EDS’s ability to clear fault codes. You might be thinking that’s like taking a heap of morphine so you can’t feel your sprained ankle – it just masks the problem – but the funny thing about fault codes is the first step is to see whether it was a one-off or a genuine problem.

Fault codes can occur for any number of reasons, from genuine problems to random one-off occurrences that maybe never be replicated. So, the first step after recording what the error code is and looking up exactly what that means, is to clear the code and see if it comes back. In our experience, about half the time the Check Engine Light stays off, and half the time it comes back on. If it does come back on, you know that you have a genuine fault you need to check, and it’s time to investigate.

Let’s put this in perspective for a moment and see how much money an Engine Data Scan could save you just by allowing you to clear a false Check Engine Light error code. Let’s look at the best-case scenario. You have roadside assistance and can get the vehicle towed into a mechanic, who miraculously can look at it later that afternoon. They plug their thousands and thousands of dollars of scanning tools into your vehicle, read an error code that says ‘ABS sensor’ so as a good mechanic they investigate. They pull each sensor off (because it didn’t say which one has failed), clean each sensor, inspect the wiring and the loom plug and replace it. There’s just shy of two hours of labour including a decent test drive by the apprentice to make sure the light doesn’t come back on. All up you’re looking at a $280 bill, plus you’re out a day’s time, for a conclusion you could very well have come to yourself.

Make the way-less-than-$100 purchase price of an EDS look like a bargain, right?